Wisconsin (WI) Utility Contractor Actual Exam 2026-2027 |
Comprehensive Question Practice Test with Answers &
Rationales| Free Pdf Access - 130 Questions
Section 1: Excavation and Trenching Safety (Questions 1-15)
1 A contractor plans a trench excavation in Type C soil to a depth of 20 feet. The nearest underground utility line
is 4 feet from the trench edge. Which protective system is most appropriate, considering OSHA's tabulated data
limitations and the proximity of the utility?
A) Slope the trench walls to a 1.5H:1V angle and use a trench shield for the top 10 feet only
B) Install a soldier beam and lagging system designed by a registered professional engineer for the full depth
C) Use a hydraulic shoring system rated for Type C soil with a maximum vertical spacing of 2 feet
D) Excavate in open-cut method with a 34° angle of repose and place excavated spoil at least 3 feet from the
edge
Answer: B
Rationale: OSHA requires that protective systems for trenches over 20 feet deep be designed by a registered
professional engineer (1926.652(b)(3)). Type C soil has a maximum allowable slope of 1.5H:1V (34°), but at 20 ft
depth, a simple slope may encroach on the utility line (4 ft away). A soldier beam and lagging system engineered
for the full depth ensures stability and avoids the utility. Option A is incorrect because tabulated data often limit
shield use to 20 ft, but partial shielding is unsafe. Option C uses improper spacing for Type C. Option D violates
spoil distance (must be 2 ft, but here 3 ft is acceptable, but the slope alone may not be adequate given the utility
proximity and depth).
2 During a trench rescue, a worker is found buried up to the chest in soil after a collapse. The rescue team has a
vacuum excavator and hand tools. What is the primary hazard that must be mitigated before extraction begins?
A) Risk of secondary collapse from vibration of the vacuum excavator
B) Crush syndrome from prolonged compression of lower extremities
C) Hypoxia due to oxygen displacement by soil gases in the trench
D) Air embolism from rapid decompression after removal of soil pressure
Answer: B
Rationale: Crush syndrome (traumatic rhabdomyolysis) occurs when muscle tissue is compressed for an extended
period, releasing toxins upon release. Before extraction, rescue teams must ensure medical support is available to
manage reperfusion complications. Option A is a risk but secondary; the immediate life threat is crush syndrome.
Option C is less likely as the worker's airway is above soil. Option D is not typical in trench rescues.
3 A trench is excavated to a depth of 14 feet in layered soil: the top 6 feet are Type A, the next 5 feet are Type B,
and the bottom 3 feet are Type C. The contractor proposes a single slope from the top edge to the bottom. What
is the minimum overall slope angle required by OSHA?
A) 34° (1.5H:1V) because the most restrictive soil type governs the entire slope
B) 45° (1H:1V) because the majority of the depth is Type A and B
C) 53° (0.75H:1V) for the Type A portion, 45° for Type B, and 34° for Type C, with a benched configuration
D) A sloping design is not permitted for layered soils; only shoring or shielding may be used
Answer: A
Rationale: OSHA 1926 Subpart P Appendix B states that when a trench has layered soils, the slope must be
determined by the most restrictive (weakest) soil type present. Type C soil (34° or 1.5H:1V) is the weakest, so the
,entire slope must conform to that angle. Option B and C are incorrect because they do not use the most restrictive
soil. Option D is false; sloping is allowed if designed per the weakest layer.
4 An engineer designs a trench shield (box) for a 12-foot-deep excavation in Type B soil. The shield's sidewalls
are 0.5 inches thick steel. During installation, the shield is placed such that the top edge is 2 feet below the
ground surface. Is this compliant with OSHA's requirements for shield use?
A) Yes, as long as the shield extends to the bottom of the trench and the gap above is sloped back appropriately
B) No, because the shield must extend at least 18 inches above the top of the trench to prevent cave-ins from the
surface
C) No, because the shield must be installed flush with the ground surface to protect against surface debris
D) Yes, if the shield is designed by a registered professional engineer and the gap is less than 2 feet
Answer: A
Rationale: OSHA 1926.652(g)(1)(iv) allows shields to be placed with the top edge below the trench's top if the
exposed area above the shield is sloped to prevent cave-ins. The shield must still protect the full depth. Option B is
incorrect; there is no 18-inch requirement above the trench. Option C is false; flush installation is not mandated.
Option D is not required if tabulated data are used, but the condition of sloping above is necessary.
5 A contractor is excavating a trench adjacent to a 3-story building with a shallow foundation (footing depth 4
feet). The trench depth is 10 feet, and the distance from the trench edge to the building foundation is 6 feet.
What additional measure is required beyond standard protective systems?
A) Underpinning the building foundation before excavation begins
B) Installation of a vibration monitoring system on the building
C) A registered professional engineer must determine if the excavation affects the stability of the building
D) No additional measures are needed because the trench is deeper than the footing and more than 5 feet away
Answer: C
Rationale: OSHA 1926.651(j)(2) requires that when excavations are deeper than the adjacent foundation and within
a distance equal to the depth of the excavation (here 10 ft), a registered professional engineer must assess stability
and design protective measures. Underpinning (A) may be one outcome but is not automatically required. Vibration
monitoring (B) is not mandated. Option D is incorrect because the distance (6 ft) is less than the depth (10 ft),
triggering the evaluation.
6 A utility crew is working in a 8-foot-deep trench that has been classified as Type B soil. They use a hydraulic
shoring system with vertical rails spaced 6 feet apart horizontally and 4 feet vertically. The manufacturer's
tabulated data for Type B soil specify a maximum vertical spacing of 5 feet and horizontal spacing of 8 feet. Is
this installation compliant?
A) Yes, because the vertical spacing is less than the maximum allowed
B) No, because the horizontal spacing exceeds 5 feet for Type B soil
C) No, because the vertical spacing must not exceed 4 feet for Type B
D) Yes, because both spacings are within the manufacturer's limits
Answer: D
Rationale: The manufacturer's tabulated data allow vertical spacing up to 5 ft and horizontal up to 8 ft. The
installation uses 4 ft vertical (5) and 6 ft horizontal (8), so it is compliant. Option B is incorrect because 6 ft is less
than 8 ft. Option C is false; the limit is 5 ft, not 4 ft. Option A is true but incomplete; both dimensions must be
within limits, which they are.
7 During a trenching operation, a gas detector alarms at 15% LEL for methane. The trench is 12 feet deep. What
is the correct immediate action according to OSHA?
,A) Evacuate the trench and ventilate continuously until readings are below 10% LEL
B) Continue working but require all workers to wear respirators with organic vapor cartridges
C) Lower the gas detector into the trench and retest after 5 minutes; if reading persists, evacuate
D) Evacuate the trench and notify the utility company to shut off the gas supply
Answer: A
Rationale: OSHA 1926.651(g)(1) requires that when an oxygen deficiency or hazardous atmosphere is detected,
employees must be removed from the hazardous area until the hazard is eliminated. Continuous ventilation is the
primary control. 15% LEL is above the 10% action level. Option B is incorrect because respirators are not a
substitute for ventilation and evacuation. Option C delays evacuation. Option D may be needed but the immediate
action is evacuation and ventilation.
8 A contractor is using a benched excavation system in Type A soil to a total depth of 18 feet. The bench width is
3 feet. Is this configuration compliant with OSHA's benching requirements?
A) Yes, because Type A soil allows benching with a maximum total height of 20 feet
B) No, because the bench width must be at least 4 feet for Type A soil
C) No, because benching is not permitted in Type A soil at depths over 15 feet
D) Yes, because the bench width is adequate for worker access
Answer: B
Rationale: OSHA Appendix B requires that for Type A soil, the minimum bench width is 4 feet. A 3-foot bench is
insufficient. Option A is false; the depth limit for benching in Type A is 20 ft, but the width requirement is not met.
Option C is incorrect; benching is allowed in Type A up to 20 ft. Option D is irrelevant; the width must meet the
standard.
9 A trench is excavated to a depth of 9 feet in Type C soil. The contractor decides to use a trench box (shield) that
is 8 feet tall. The box is placed on the bottom of the trench, leaving a 1-foot gap at the top. The soil above the
box is sloped back at 1.5H:1V. Is this arrangement acceptable?
A) Yes, because the shield protects the lower portion and the slope protects the upper portion
B) No, because the shield must extend at least to the top of the trench
C) No, because the slope angle for Type C soil is 1.5H:1V, but the shield must be at least 9 feet tall
D) Yes, if the shield is designed to handle the full depth and the gap is less than 2 feet
Answer: A
Rationale: OSHA allows shields to be used with a gap at the top if the exposed area is sloped to the appropriate
angle. The slope of 1.5H:1V for Type C is correct, and the shield covers the lower 8 ft. The total protection (slope +
shield) covers the full depth. Option B is false; the shield does not need to extend to the top. Option C is incorrect
because the shield height is not required to match the trench depth. Option D is irrelevant; the shield design must
be per tabulated data or engineer, but the arrangement is acceptable.
10 A contractor plans to use a sloping system for a 15-foot-deep trench in Type B soil. The slope angle is 45°
(1H:1V). However, a large rock (3 feet in diameter) is encountered at the bottom of the slope. What should the
contractor do?
A) Remove the rock carefully and continue with the same slope
B) Reevaluate the soil classification because the presence of rock may indicate Type A soil, allowing a steeper
slope
C) Notch the slope around the rock and install rock bolts to secure it
D) Re-slope to a 34° angle (1.5H:1V) for the entire trench because the rock reduces stability
Answer: A
Rationale: OSHA requires that loose rock or boulders be removed or secured to prevent falling into the trench.
, Removing the rock is the standard approach. Option B is incorrect; rock does not change soil classification of the
surrounding soil. Option C is not typical; rock bolting may be used for larger formations but not for a single
boulder. Option D is unnecessary if the rock is removed.
11 A contractor plans to excavate a 12-foot-deep trench in Type C soil. The trench will be 4 feet wide and 50 feet
long. The contractor intends to use a trench box with a maximum allowable depth rating of 15 feet. However,
the soil is saturated due to recent heavy rain. Which of the following actions is most critical to ensure safety
under these conditions?
A) Increase the width of the trench to reduce sidewall pressure.
B) Install a dewatering system to lower the water table before excavation.
C) Use the trench box without additional shoring because its rating exceeds the depth.
D) Slope the trench walls to a 1:1 angle (45°) instead of using the trench box.
Answer: B
Rationale: Saturated soil significantly increases hydrostatic pressure and reduces soil cohesion, elevating the risk of
cave-ins. Dewatering is essential to stabilize the soil before excavation. Trench boxes require stable soil conditions;
using one in saturated soil without dewatering can lead to failure even if the depth rating is adequate. Sloping to 1:1
is insufficient for Type C soil (requires 1.5:1 maximum angle). Widening the trench does not address the root
cause.
12 An excavation site has a trench 8 feet deep in Type B soil. A competent person inspects the site and notes that a
spoil pile is placed 1 foot from the edge of the trench, and the pile height is 5 feet. The trench is 6 feet wide.
Which of the following best describes the primary hazard and the required corrective action?
A) The spoil pile imposes additional surcharge load; it must be moved at least 2 feet from the edge.
B) The spoil pile imposes additional surcharge load; it must be moved at least 5 feet from the edge.
C) The spoil pile height violates the maximum allowable height of 4 feet; it must be reduced.
D) The spoil pile distance is acceptable because it is less than the trench depth; no action is needed.
Answer: B
Rationale: OSHA requires spoil piles to be placed at least 2 feet from the edge of an excavation, but for a trench of
this depth and soil type, the surcharge load from a 5-foot-high pile so close to the edge significantly increases the
risk of cave-in. The general guideline is that spoil should be set back a distance equal to at least the depth of the
trench (8 feet) or more, but the minimum is 2 feet. However, given the height and proximity, a greater setback (5
feet) is prudent to reduce surcharge. Option B reflects this standard practice. Option A's 2 feet is the absolute
minimum and may not be sufficient here.
13 A utility contractor is working in a trench that is 10 feet deep and 5 feet wide, with a trench box installed. The
competent person observes that the trench box is 12 feet long, but the trench section being excavated is 15 feet
long. The contractor plans to extend the excavation without moving the box. Which of the following is the most
appropriate safety measure?
A) Extend the trench box to cover the entire length by adding an additional panel.
B) Slope the ends of the trench to a 1.5:1 angle where the box does not cover.
C) Do not allow workers to enter the unprotected portion of the trench.
D) Reduce the trench depth to 8 feet to allow the box to cover the entire length.
Answer: C
Rationale: The trench box provides protection only where it is installed. Workers must not be in any part of the
trench that is not shielded, sloped, or otherwise protected. The correct immediate action is to ensure no entry into
the unprotected area. Sloping the ends (option B) is a possible solution but may not be feasible in tight spaces; the
most critical safety measure is to prevent exposure. Extending the box (option A) is ideal but may not be
Comprehensive Question Practice Test with Answers &
Rationales| Free Pdf Access - 130 Questions
Section 1: Excavation and Trenching Safety (Questions 1-15)
1 A contractor plans a trench excavation in Type C soil to a depth of 20 feet. The nearest underground utility line
is 4 feet from the trench edge. Which protective system is most appropriate, considering OSHA's tabulated data
limitations and the proximity of the utility?
A) Slope the trench walls to a 1.5H:1V angle and use a trench shield for the top 10 feet only
B) Install a soldier beam and lagging system designed by a registered professional engineer for the full depth
C) Use a hydraulic shoring system rated for Type C soil with a maximum vertical spacing of 2 feet
D) Excavate in open-cut method with a 34° angle of repose and place excavated spoil at least 3 feet from the
edge
Answer: B
Rationale: OSHA requires that protective systems for trenches over 20 feet deep be designed by a registered
professional engineer (1926.652(b)(3)). Type C soil has a maximum allowable slope of 1.5H:1V (34°), but at 20 ft
depth, a simple slope may encroach on the utility line (4 ft away). A soldier beam and lagging system engineered
for the full depth ensures stability and avoids the utility. Option A is incorrect because tabulated data often limit
shield use to 20 ft, but partial shielding is unsafe. Option C uses improper spacing for Type C. Option D violates
spoil distance (must be 2 ft, but here 3 ft is acceptable, but the slope alone may not be adequate given the utility
proximity and depth).
2 During a trench rescue, a worker is found buried up to the chest in soil after a collapse. The rescue team has a
vacuum excavator and hand tools. What is the primary hazard that must be mitigated before extraction begins?
A) Risk of secondary collapse from vibration of the vacuum excavator
B) Crush syndrome from prolonged compression of lower extremities
C) Hypoxia due to oxygen displacement by soil gases in the trench
D) Air embolism from rapid decompression after removal of soil pressure
Answer: B
Rationale: Crush syndrome (traumatic rhabdomyolysis) occurs when muscle tissue is compressed for an extended
period, releasing toxins upon release. Before extraction, rescue teams must ensure medical support is available to
manage reperfusion complications. Option A is a risk but secondary; the immediate life threat is crush syndrome.
Option C is less likely as the worker's airway is above soil. Option D is not typical in trench rescues.
3 A trench is excavated to a depth of 14 feet in layered soil: the top 6 feet are Type A, the next 5 feet are Type B,
and the bottom 3 feet are Type C. The contractor proposes a single slope from the top edge to the bottom. What
is the minimum overall slope angle required by OSHA?
A) 34° (1.5H:1V) because the most restrictive soil type governs the entire slope
B) 45° (1H:1V) because the majority of the depth is Type A and B
C) 53° (0.75H:1V) for the Type A portion, 45° for Type B, and 34° for Type C, with a benched configuration
D) A sloping design is not permitted for layered soils; only shoring or shielding may be used
Answer: A
Rationale: OSHA 1926 Subpart P Appendix B states that when a trench has layered soils, the slope must be
determined by the most restrictive (weakest) soil type present. Type C soil (34° or 1.5H:1V) is the weakest, so the
,entire slope must conform to that angle. Option B and C are incorrect because they do not use the most restrictive
soil. Option D is false; sloping is allowed if designed per the weakest layer.
4 An engineer designs a trench shield (box) for a 12-foot-deep excavation in Type B soil. The shield's sidewalls
are 0.5 inches thick steel. During installation, the shield is placed such that the top edge is 2 feet below the
ground surface. Is this compliant with OSHA's requirements for shield use?
A) Yes, as long as the shield extends to the bottom of the trench and the gap above is sloped back appropriately
B) No, because the shield must extend at least 18 inches above the top of the trench to prevent cave-ins from the
surface
C) No, because the shield must be installed flush with the ground surface to protect against surface debris
D) Yes, if the shield is designed by a registered professional engineer and the gap is less than 2 feet
Answer: A
Rationale: OSHA 1926.652(g)(1)(iv) allows shields to be placed with the top edge below the trench's top if the
exposed area above the shield is sloped to prevent cave-ins. The shield must still protect the full depth. Option B is
incorrect; there is no 18-inch requirement above the trench. Option C is false; flush installation is not mandated.
Option D is not required if tabulated data are used, but the condition of sloping above is necessary.
5 A contractor is excavating a trench adjacent to a 3-story building with a shallow foundation (footing depth 4
feet). The trench depth is 10 feet, and the distance from the trench edge to the building foundation is 6 feet.
What additional measure is required beyond standard protective systems?
A) Underpinning the building foundation before excavation begins
B) Installation of a vibration monitoring system on the building
C) A registered professional engineer must determine if the excavation affects the stability of the building
D) No additional measures are needed because the trench is deeper than the footing and more than 5 feet away
Answer: C
Rationale: OSHA 1926.651(j)(2) requires that when excavations are deeper than the adjacent foundation and within
a distance equal to the depth of the excavation (here 10 ft), a registered professional engineer must assess stability
and design protective measures. Underpinning (A) may be one outcome but is not automatically required. Vibration
monitoring (B) is not mandated. Option D is incorrect because the distance (6 ft) is less than the depth (10 ft),
triggering the evaluation.
6 A utility crew is working in a 8-foot-deep trench that has been classified as Type B soil. They use a hydraulic
shoring system with vertical rails spaced 6 feet apart horizontally and 4 feet vertically. The manufacturer's
tabulated data for Type B soil specify a maximum vertical spacing of 5 feet and horizontal spacing of 8 feet. Is
this installation compliant?
A) Yes, because the vertical spacing is less than the maximum allowed
B) No, because the horizontal spacing exceeds 5 feet for Type B soil
C) No, because the vertical spacing must not exceed 4 feet for Type B
D) Yes, because both spacings are within the manufacturer's limits
Answer: D
Rationale: The manufacturer's tabulated data allow vertical spacing up to 5 ft and horizontal up to 8 ft. The
installation uses 4 ft vertical (5) and 6 ft horizontal (8), so it is compliant. Option B is incorrect because 6 ft is less
than 8 ft. Option C is false; the limit is 5 ft, not 4 ft. Option A is true but incomplete; both dimensions must be
within limits, which they are.
7 During a trenching operation, a gas detector alarms at 15% LEL for methane. The trench is 12 feet deep. What
is the correct immediate action according to OSHA?
,A) Evacuate the trench and ventilate continuously until readings are below 10% LEL
B) Continue working but require all workers to wear respirators with organic vapor cartridges
C) Lower the gas detector into the trench and retest after 5 minutes; if reading persists, evacuate
D) Evacuate the trench and notify the utility company to shut off the gas supply
Answer: A
Rationale: OSHA 1926.651(g)(1) requires that when an oxygen deficiency or hazardous atmosphere is detected,
employees must be removed from the hazardous area until the hazard is eliminated. Continuous ventilation is the
primary control. 15% LEL is above the 10% action level. Option B is incorrect because respirators are not a
substitute for ventilation and evacuation. Option C delays evacuation. Option D may be needed but the immediate
action is evacuation and ventilation.
8 A contractor is using a benched excavation system in Type A soil to a total depth of 18 feet. The bench width is
3 feet. Is this configuration compliant with OSHA's benching requirements?
A) Yes, because Type A soil allows benching with a maximum total height of 20 feet
B) No, because the bench width must be at least 4 feet for Type A soil
C) No, because benching is not permitted in Type A soil at depths over 15 feet
D) Yes, because the bench width is adequate for worker access
Answer: B
Rationale: OSHA Appendix B requires that for Type A soil, the minimum bench width is 4 feet. A 3-foot bench is
insufficient. Option A is false; the depth limit for benching in Type A is 20 ft, but the width requirement is not met.
Option C is incorrect; benching is allowed in Type A up to 20 ft. Option D is irrelevant; the width must meet the
standard.
9 A trench is excavated to a depth of 9 feet in Type C soil. The contractor decides to use a trench box (shield) that
is 8 feet tall. The box is placed on the bottom of the trench, leaving a 1-foot gap at the top. The soil above the
box is sloped back at 1.5H:1V. Is this arrangement acceptable?
A) Yes, because the shield protects the lower portion and the slope protects the upper portion
B) No, because the shield must extend at least to the top of the trench
C) No, because the slope angle for Type C soil is 1.5H:1V, but the shield must be at least 9 feet tall
D) Yes, if the shield is designed to handle the full depth and the gap is less than 2 feet
Answer: A
Rationale: OSHA allows shields to be used with a gap at the top if the exposed area is sloped to the appropriate
angle. The slope of 1.5H:1V for Type C is correct, and the shield covers the lower 8 ft. The total protection (slope +
shield) covers the full depth. Option B is false; the shield does not need to extend to the top. Option C is incorrect
because the shield height is not required to match the trench depth. Option D is irrelevant; the shield design must
be per tabulated data or engineer, but the arrangement is acceptable.
10 A contractor plans to use a sloping system for a 15-foot-deep trench in Type B soil. The slope angle is 45°
(1H:1V). However, a large rock (3 feet in diameter) is encountered at the bottom of the slope. What should the
contractor do?
A) Remove the rock carefully and continue with the same slope
B) Reevaluate the soil classification because the presence of rock may indicate Type A soil, allowing a steeper
slope
C) Notch the slope around the rock and install rock bolts to secure it
D) Re-slope to a 34° angle (1.5H:1V) for the entire trench because the rock reduces stability
Answer: A
Rationale: OSHA requires that loose rock or boulders be removed or secured to prevent falling into the trench.
, Removing the rock is the standard approach. Option B is incorrect; rock does not change soil classification of the
surrounding soil. Option C is not typical; rock bolting may be used for larger formations but not for a single
boulder. Option D is unnecessary if the rock is removed.
11 A contractor plans to excavate a 12-foot-deep trench in Type C soil. The trench will be 4 feet wide and 50 feet
long. The contractor intends to use a trench box with a maximum allowable depth rating of 15 feet. However,
the soil is saturated due to recent heavy rain. Which of the following actions is most critical to ensure safety
under these conditions?
A) Increase the width of the trench to reduce sidewall pressure.
B) Install a dewatering system to lower the water table before excavation.
C) Use the trench box without additional shoring because its rating exceeds the depth.
D) Slope the trench walls to a 1:1 angle (45°) instead of using the trench box.
Answer: B
Rationale: Saturated soil significantly increases hydrostatic pressure and reduces soil cohesion, elevating the risk of
cave-ins. Dewatering is essential to stabilize the soil before excavation. Trench boxes require stable soil conditions;
using one in saturated soil without dewatering can lead to failure even if the depth rating is adequate. Sloping to 1:1
is insufficient for Type C soil (requires 1.5:1 maximum angle). Widening the trench does not address the root
cause.
12 An excavation site has a trench 8 feet deep in Type B soil. A competent person inspects the site and notes that a
spoil pile is placed 1 foot from the edge of the trench, and the pile height is 5 feet. The trench is 6 feet wide.
Which of the following best describes the primary hazard and the required corrective action?
A) The spoil pile imposes additional surcharge load; it must be moved at least 2 feet from the edge.
B) The spoil pile imposes additional surcharge load; it must be moved at least 5 feet from the edge.
C) The spoil pile height violates the maximum allowable height of 4 feet; it must be reduced.
D) The spoil pile distance is acceptable because it is less than the trench depth; no action is needed.
Answer: B
Rationale: OSHA requires spoil piles to be placed at least 2 feet from the edge of an excavation, but for a trench of
this depth and soil type, the surcharge load from a 5-foot-high pile so close to the edge significantly increases the
risk of cave-in. The general guideline is that spoil should be set back a distance equal to at least the depth of the
trench (8 feet) or more, but the minimum is 2 feet. However, given the height and proximity, a greater setback (5
feet) is prudent to reduce surcharge. Option B reflects this standard practice. Option A's 2 feet is the absolute
minimum and may not be sufficient here.
13 A utility contractor is working in a trench that is 10 feet deep and 5 feet wide, with a trench box installed. The
competent person observes that the trench box is 12 feet long, but the trench section being excavated is 15 feet
long. The contractor plans to extend the excavation without moving the box. Which of the following is the most
appropriate safety measure?
A) Extend the trench box to cover the entire length by adding an additional panel.
B) Slope the ends of the trench to a 1.5:1 angle where the box does not cover.
C) Do not allow workers to enter the unprotected portion of the trench.
D) Reduce the trench depth to 8 feet to allow the box to cover the entire length.
Answer: C
Rationale: The trench box provides protection only where it is installed. Workers must not be in any part of the
trench that is not shielded, sloped, or otherwise protected. The correct immediate action is to ensure no entry into
the unprotected area. Sloping the ends (option B) is a possible solution but may not be feasible in tight spaces; the
most critical safety measure is to prevent exposure. Extending the box (option A) is ideal but may not be
